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List Honaker primes
The number 131 is the 32nd prime number. It is a Honaker prime because the sum of its digits (1+3+1) equals the sum of the digit...

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Hoax Numbers
A Hoax Number (OEIS A019506) is defined as a composite number, whose sum of digits is equal to the sum of digits of its distinct...

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commutative?
Given the handle to a binary function that takes two ordinary numbers, test if the function is commutative.

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Champernowne Constant
The <http://en.wikipedia.org/wiki/Champernowne_constant Champernowne constant> is a real number whose digits in decimal represen...

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Is it an Armstrong number?
An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself. Fo...

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P-smooth numbers
This Challenge is to find <https://en.wikipedia.org/wiki/Smooth_number P-smooth number> partial sets given P and a max series va...

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Fermat's Last Theorem - Fermat's conjecture
Fermat's Last Theorem (sometimes called Fermat's conjecture, especially in older texts) states that no three positive integers a...

5 years ago

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Happy 2013...
Happy 2013, everyone! An interesting tidbit about 2013 is that it is the first year since 1987 to contain four different digits...

5 years ago

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Largest Twin Primes
<http://en.wikipedia.org/wiki/Twin_prime Twin primes> are primes p1, p2 = p1 + 2 such that both p1 and p2 are prime numbers. Giv...

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Lychrel Number Test (Inspired by Project Euler Problem 55)
The task for this problem is to create a function that takes a number _n_ and tests if it might be a Lychrel number. This is, re...

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Determine if input is a perfect number
A <http://en.wikipedia.org/wiki/Perfect_number/ perfect number> occurs whent the sum of all divisors of a positive integer, exce...

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Determine if input is a Narcissistic number
<http://en.wikipedia.org/wiki/Narcissistic_number Narcissistic number> is a number that is the sum of its own digits each raised...

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Mersenne Primes
A Mersenne prime is a prime number of the form M = 2^p - 1, where p is another prime number. For example, 31 is a Mersenne prim...

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Numbers with prime factors 2, 3 and 5.
Make a function which takes one positive integer n and returns a matrix with the numbers of the form (2^i)*(3^j)*(5^k) which are...

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Energy of a photon
*&#9883 &#9762 &#9883 &#9762 &#9883 &#9762 &#9883* Given the frequency F of a photon in giga hertz. Find energy E of this...

5 years ago

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Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock.
Submit your answer to this problem a multiple of 5 seconds after the hour. Your answer is irrelevant; the only thing that matte...

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Find vampire numbers
A <http://en.wikipedia.org/wiki/Vampire_number vampire number> is a number v that is the product of two numbers x and y such th...

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Generate a Parasitic Number
This problem is the next step up from <http://www.mathworks.com/matlabcentral/cody/problems/156-parasitic-numbers Problem 156>. ...

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Kaprekar numbers
Test if the input is a Kaprekar number: <http://mathworld.wolfram.com/KaprekarNumber.html>. Return a logical true or false. ...

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Parasitic numbers
Test whether the first input x is an n-parasitic number: <http://en.wikipedia.org/wiki/Parasitic_number>. ( _n_ is the second in...

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Index of a Rational number
The set of real numbers are infinite. They are so many that real numbers can't even be enumerated. However, unlike real numbers ...

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nth Rational Number
Return the nth rational number. This is the inverse to Problem <http://www.mathworks.com/matlabcentral/cody/problems/1471 1...

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Polygonal numbers
The task of <http://www.mathworks.co.uk/matlabcentral/cody/problems/5 Problem 5> is to calculate triangular numbers. By playing ...

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Which Prime
Given two prime numbers, specify the relation between them i.e. - 'Twin Prime', 'Cousin Prime', 'Sexy Prime' or 'None'

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Is this number Munchhausen Narcissistic?
In this problem, simply return 1 if a supplied number is Munchhausen narcissistic or 0 if not. Example 153 is narcissistic...

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Narcissistic number ?
Inspired by Problem 2056 created by Ted. In recreational number theory, a narcissistic number is a number that is the sum of ...

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Polite numbers. N-th polite number.
A polite number is an integer that sums of at least two consecutive positive integers. For example _7 = 3+4_ so 7 is a polite...

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Polite numbers. Politeness.
A polite number is an integer that sums of two or more consecutive positive integers. Politeness of a positive integer is a num...

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Generalised Hamming Number
Inspired by Project Euler n°204 and Problem 1308 by James A generalised Hamming number of type n, has no prime factor larger ...

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Armstrong Number
Determine whether the given input n-digit number is Armstrong Number or not. Return True if it is an Armstrong Number. An n-D...

5 years ago